Last weekend I posted a couple of questions about the geometry of the
parts at the base of the gearshift lever for the 3-rail gearbox. The
Reverse Baulk mechanism, where you have to push down on the lever to get
into reverse, wasn't working. You didn't have to press down. The screw
passed right under the Reverse Baulk Plate. It had been that way for a
long time. I flunked a state MV inspection once because when the MORON
got in to test the brakes he put it into Reverse instead of 1st.
I installed the rebush kit, expecting that this would cure the problem.
It didn't, so I posted my questions. Received 2 private replies. Bill
Birney informed me that the nylon ball at the base of the lever rides
directly in the socket in the top cover extension. Kris Cotton told me
that if I had assembled everything correctly, then most likely the
extension housing itself was worn. I had, and it was. Andy Mace dropped
me a "how's it going". Thanks for the replies, Bill and Kris and Andy.
Well, I fixed it. I bought National Mfg. Co. part number N247-825 V1711,
furniture glide, 1 1/4", neutral (no financial interest, etc.) It's the
same diameter as the ball, mostly flat but cupped around the edge.
Removed the flat part with a rotary rasp and a rattail file, so that all
that was left was the cupped rim. After a couple of test fittings and
adjustments, I installed it in the bottom of the socket in the extension
casting, using a good general purpose 2-part epoxy. The nylon ball at
the base of the lever (138685, Bush, Spherical, available from all the
usual suspects and included in the rebush kit, at least the one I
bought) now rides on my new nylon insert, instead of directly on the
aluminum. Shifting is nice and smooth, and you definitely have to press
down to get into reverse!
Mr. Mace expressed surprise that the aluminum had worn out, instead of
the nylon ball. Here's what I think happens. You get some buildup of
grit between the nylon ball and the aluminum socket. One surface is much
harder than the other. The grit particles embed themselves in the
_softer_ surface, and ride it across the harder surface. The harder
surface gets abraded! Think of a powdered cleanser pressed between a
sponge and a countertop. The cleanser moves with the sponge, and the
counter gets scoured.
In his reply, Kris Cotton told me he has tossed a number of extensions
because the socket was worn out (that is what you said, isn't it?).
These extensions do wear out, and I don't think anybody is casting them
anymore. If any parts suppliers are listening, how about a proper liner
for the socket, maybe 1/16" thick with a smaller ball to match?
Until they do, I have 3 spares of National Mfg Co. N247-825 V1711 - they
come 4 to the pack!
Bill Kelly
'62 Herald with restored 3-rail shifter
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